Reproducing apparatus



y 19, 1959 K. A. BARSTROM ETAL 2,887,353;

REPRODUCING APPARATUS 2 Sheets-Sheet 1 Filed July 3, 1956 2565/ V6 A AApPL F/ER INVENTORS KNUT A. BARSTROM ARTHUR A. KLEBBA FIG.2

I II II II In tr I FIG. 3

ATTORNEY United States Patent'O REPRODUCIN G APPARATUS Knut A. Barstrom,Columbia, and Arthur A. Klehba, Thompsonville, Conn., assignors to GrayResearch and Development Company, Inc., a corporation of New YorkApplication July 3, 1956, Serial No. 595,676

12 Claims. (Cl. 346-74) bars for producing point by point contactsthrough the paper upon which the record is to be produced withconductive blades. Experience has shown that such helical wires orstrips are highly susceptible to non-uniform erosion due to thecomposition of the paper and the passage of current. Moreover, theconventional apparatus as exemplified by these patents has severelylimited the speed of operation in order to prevent undesirable damage tothe paper itself. I

By virtue of the present invention, in addition to solving theseproblems, inertia forces have been reduced, wear diminished andregistration improved. Consequently, in accordance with this inventionmuch higher writing speeds and higher resolution have been achieved thanhas been possible with conventional apparatus.

The reproducing apparatus constituting the subject matter of thisinvention comprises a rotary drum containing a peripheral helical grooveadapted to receive a ball, the groove having ball inlet and dischargeportions adjacent the ends respectively of the drum, means defining araceway adjacent the drum constraining the ball to traverse the groove,and ball directing means adjacent the inlet portion for introducing theball into the groove and raceway. The groove preferably has anintermediate portion of constant pitch, an inlet portion increasing inpitch in the direction of movement of the ball, and a discharge portiondecreasing in pitch in the direction of movement of the ball. Byemploying a ball in this manner, erosion is distributed over its entirespherical surface, greatly extending the life of the apparatus ascompared with equipment employing helical wires or strips.

The groove is preferably a circular arc in cross section of less than180 and the raceway defined by strips having opposed straight edges ofrelatively low coefficient of friction such as nylon or Teflon. The balldirecting means preferably contains a plurality of balls and assumes theform of a conveying tube interconnecting the inlet and dischargeportions of the groove. Such tube is preferably maintained full of ballsadvanced towards the inlet portion of the groove by each ball deliveredfrom the discharge portion of the groove. Thus, it will follow, thatsuch use of multiple balls even further distributes erosion and wear andassures a long life to the apparatus.

A more complete understanding of the invention will follow from adescription of the accompanying drawings wherein:

Fig. 1 is a schematic perspective showing, partially broken away, ofportions of a system incorporating the present invention;

Fig. 2 is an elevation of a drum produced in accordance with the presentinvention;

Fig. 3 is an end elevation of the drum shown in Fig. 2;

Fig. 4 is a plan view, partially broken away, of a practical structureincorporating the present invention;

Fig. 5 is a section taken along line 55 of Fig. 4 on a slightly enlargedscale; and

Fig. 6 is a section taken along line 66 of Fig. 4.

The drum 10 as shown in Fig. 1 contains a helical groove 12 whosecross-section is a circular are less than 180. At the left end of thedrum 10 as shown in Fig. 1, there is an undercut portion 14 of slightlyincreasing width extending approximately 270 about the periphery of thedrum to a point 16 at which it communicates with an inlet portion 18 ofthe groove 12 having an increasing pitch to provide uniform accelerationto a ball introduced thereinto until it reaches a point 20 at which itjoins the intermediate portion 22 of the groove 12 of constant pitch.This intermediate portion of the groove extends to a point 24 at whichit joins, a discharge portion 26 of the groove of decreasing pitch so asto impart constant deceleration to a ball received therein. As the drum10 is rotated about the axis of its shaft 28, a ball 30 received in thegroove 12 is retained therein by a raceway defined by strips 32 ofmaterial such as nylon or Teflon having a low coefficient of'frictionand tending to lubricate the ball, the strips 32 having straight edges34 defining a raceway. By virtue of this arrangement, it will followthat when a ball 30 is introduced at the left end of the drum, itsinitial horizontal movement will be very slight, whereupon it willreceive a constant acceleration in the inlet portion 18 of the grooveuntil it enters the intermediate portion 22 of constant pitch whereuponits horizontal travel will be uniform until it enters the dischargeportion 26 of the groove in which it will be uniformly decelerated so asto receive a progressively decreasing horizontal movement. Suitablytreated paper 36 fed as shown in the direction of the arrow 38 will rideover the strips 32 for engagement with the balls 30 and under a blade 40of conducting material. As depicted in Fig. 1, a signal to be translatedwill be supplied to a receiver amplifier 42 having output leads 44 and46 connected to the shaft 28 and blade 40 respectively. Since the shaft,drum and balls are conducting, the desired electrolytic action will beproduced by the passage of current through this circuit.

The assumed direction of rotation of the drum is in dicated by the arrow48 and the corresponding direction of movement of the ball 30 by thearrow 50.

As shown in Fig. 4, a tube 52 having a substantially 'C-shapedconfiguration, provides one open end 54 for the reception of the ballsas they are delivered from the discharge portion 26 of the groove 12 andits other end 56 in communication with the inlet portion 18 of thegroove 12 for supplying balls thereto. The tube 52 is maintained full ofthese balls so that upon the discharge of each ball from the groove 12,it will force those before it towards the inlet portion of the grooveuntil the leading ball actually enters the undercut portion 14. Theparts are preferably designed so that a ball enters the undercut portionafter approximately of such portion have passed the end 56 of the tube,thus avoiding any possibility of jamming.

One of a number of ways in which the assembly can be produced isdepicted in Fig. 5 wherein the drum 10 is supported between a drivingcenter 58 and a supporting center 60. The driving center is supported insuitable bearings 62 and 64 and carries a pulley 66 driven by a belt 68.The driving connection between the center 58' and the drum 10 isproduced by a pin 70 received in a complementary slot 72. The supportingframe 74 also carries the center 60 which is biased towards its end ofthe drum 10 by means of a helical spring 76. At this end of the drum, asuitable bearing 78is received internally of the drum.

Adjustment of the strips 32 defining the raceway can be effected byscrews 80 or in some other equally suitable manner.

As depicted and described for purposes of illustration, the intermediateportion of thegroove occupies an angle of 360. Departurefrom this detailand from others shown and described will suggest themselves to thoseskilled in the art as modifications of the present invention.Accordingly, the examples set forth herein should not be construed aslimiting beyond the scope of the appended claims.

We claim:

1. In reproducing-apparatus a rotary drum containing a peripheralhelical groove adapted to receive a ball, a ball in said groove, saidgroove having ball inlet and discharge portions opening at the endsrespectively of said drum, meansdefining a raceway adjacent said drumconstraining said ball to traverse said groove, ball directing meansadjacent said inlet portion for introducing said ball into said grooveand raceway, a blade extending axially of said drum and radially spacedtherefrom to define a gap with saidball, said groove having a portion ofuniform pitch adjacent said blade, and means for applying signalvoltages across said gap.

2. In reproducing apparatus as set forth in claim 1 wherein said groovehas an intermediate portion of constant pitch.

3. In reproducing apparatus as set forth in claim 1 wherein said inletportion increases in pitch in the direction of movementof said ball.

4. In reproducing apparatus as set forth in claim 1 wherein saiddischarge portion decreases in pitch in the direction of movement ofsaid ball.

5. In reproducing apparatus as set forth in claim 1 wherein said groovehas an intermediate portion of substantially constant pitch, said inletportion increases in pitch in the direction of movement of said ball,and said discharge portion decreases in pitch in the direction ofmovement of said ball.

6. In reproducing apparatus as set forth in claim 1 wherein said groovehas a circular arcuate cross section.

7. In reproducing apparatus as set forth in claim 1 wherein said groovehas a circular arcuate cross section of less than 180.

8. In reproducing apparatus as set forth in claim 1 wherein said balldirecting means contains a plurality of balls.

9. In reproducing apparatus as set forth in claim 1 wherein said inletand discharge portions are interconnected by a ball conveying tube.

10. In reproducing apparatus as set forth in claim 9 wherein said tubeis maintained full of balls advanced towards said inlet portion by eachball received from said discharge portion.

11. In reproducing apparatus as set forth in claim 1 wherein stripshaving opposed straight edges define said raceway.

12. In reproducing apparatus as set forth in claim 11 wherein saidstrips have a relatively low coefficient of friction.

References-Cited inthe file ofthis patent UNITED STATES PATENTS2,733,116 Fantham et a1 Jan. 31, 1956 ,760,840 7 Gordon Aug. 28, 19562,776,336 Clauer Jan. 1, 1957

